Electronics > Beginners
Temperature indicator circuit with LEDs
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dazz:
I love LTSpice, I just love it
Zero999:

--- Quote from: dazz on August 31, 2018, 04:16:44 pm ---I love LTSpice, I just love it

--- End quote ---
I love LTSpice too, but be careful, it can trip you up. It's easy to design a bad circuit which will work perfectly in LTSpice but perform really poorly or not work at all, in real life.

Here's an example.

.asc file
https://www.eevblog.com/forum/projects/unstable-dc-opamp-sinusoidal-signal-centering/msg1714391/#msg1714391
dazz:

--- Quote from: Hero999 on September 01, 2018, 06:13:31 pm ---
--- Quote from: dazz on August 31, 2018, 04:16:44 pm ---I love LTSpice, I just love it

--- End quote ---
I love LTSpice too, but be careful, it can trip you up. It's easy to design a bad circuit which will work perfectly in LTSpice but perform really poorly or not work at all, in real life.

Here's an example.

.asc file
https://www.eevblog.com/forum/projects/unstable-dc-opamp-sinusoidal-signal-centering/msg1714391/#msg1714391

--- End quote ---

I understand that there are limitations to what spice can simulate and I will definitely follow your advice. I'm wondering if swapping the universal opamp for a TL082 would make it fail the way it does in real life
Zero999:
Yes, the circuit will not work with the TL082, because its inputs need to be a couple of volts from the TL082's negative rail for it to work. A single supply op-amp, such as the LM358 is required for it to work.
dazz:

--- Quote from: Hero999 on September 02, 2018, 09:51:06 am ---Yes, the circuit will not work with the TL082, because its inputs need to be a couple of volts from the TL082's negative rail for it to work. A single supply op-amp, such as the LM358 is required for it to work.

--- End quote ---

I don't understand why the circuit you posted wouldn't work in RL though. The inputs of the opamps are nowhere near -15V at any time, right?
Also, the simulation I did with the TL082 seems to suggest that it would work simply by adding a coupling cap at the OP output. What am I missing here please?
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